Many baseball fans were surprised last December when the Tigers traded right-handed starting pitcher Doug Fister to the Nationals for infielder Steve Lombardozzi and left-handed pitchers Robbie Ray and Ian Krol. Ray appears to have been the centerpiece of the transaction.

The Nats selected Ray from Brentwood (Tenn.) High School in the 12th round of the 2010 First-Year Player Draft. Ray may have slipped in the Draft following word that he was intent on attending the University of Arkansas.

Ray, who is No. 1 on the Tigers' Top 20 Prospects list, is tall and thin at 6-foot-2, 195 pounds. At 22, he may still have a bit of physical development remaining.

Ray has pitched with mixed results in his career. He only pitched in one game in his rookie campaign at Class A Short Season Vermont in 2010. Ray remained in extended spring camp that year and didn't get to face opposing hitters much at all.

Ray's first full year came the following season at Class A Hagerstown, when he posted a 3.13 ERA in 20 starts. He gave up 71 hits in 89 innings, but his WHIP was inflated due to command and control issues. Ray walked 38 and finished with a 1.23 WHIP, still good, but it could have been much better without the lefty's average of just under four walks per nine innings.

Ray's 2012 season was one to forget. He pitched at Class A Advanced Potomac and made 21 starts, throwing 105 2/3 innings. Ray walked more than four batters per nine innings, regressing from the previous season, and his velocity had dropped from the mid-90s to the high-80s. He also yielded 122 hits.

Last year, things turned for the better when Ray's velocity increased to his high school level of 91-93 mph. Upon his return to Class A Advanced Potomac and at Double-A Harrisburg, his combined ERA was 3.36, down from 6.56 in 2012.

During Ray's time with the Nationals, the club made some adjustments to his mechanics. The net result was maintaining the increased velocity and improvement of his command.

After parts of five seasons in the Minors, Ray was promoted to Detroit on May 6. He made his Major League debut as a replacement starter for Anibal Sanchez in the Tigers' rotation.

Again, the results have been mixed since the callup to Detroit. Ray has had some good innings and some bad. The culprit has again been commanding his pitches and throwing strikes. A combination of big hits and too many walks have taken a toll.

There are times I have seen Ray search for a comfortable and consistent release point as he tries too hard to throw his fastball at increased velocity. On those occasions, he falls off sharply to the third-base side. Repeating a clean delivery from Ray's usual high arm slot is a goal for his continued development.

While with the Tigers, Ray has basically used a combination of a fastball, a slurve-type curveball and a changeup. I haven't seen a slider, although his curveball would seem to be at least part-slider. There are times Ray lacks movement and zip on the fastball, causing him to get hit hard by big league hitters.

The inconsistency and command issues are common for a young pitcher still developing the pitches in his repertoire and working out kinks in his delivery. For me, Ray is not quite a finished product.

Ray has been optioned back to Triple-A Toledo. He continues to work as a starter, but I think there may be some merit in his working out of the bullpen, using his good fastball and refining his secondary pitches. Once Ray has found rhythm with a complete repertoire, he may be more comfortable returning to a starting role.

Because Ray has a strong and loose arm, his current role is not as important as gaining self-confidence in his repertoire and throwing strikes with all his pitches.

Bernie Pleskoff has served as a professional scout for the Houston Astros and Seattle Mariners. Follow @BerniePleskoff on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.